US Patent 7628866 Method of cleaning wafer after etching process

A method of cleaning a wafer after an etching process is provided. A substrate having an etching stop layer, a dielectric layer, a patterned metal hard mask sequentially formed thereon is provided. Using the patterned metal hard mask, an opening is defined in the dielectric layer. The opening exposes a portion of the etching stop layer. A dry etching process is performed in the environment of helium to remove the etching stop layer exposed by the opening. A dry cleaning process is performed on the wafer surface using a mixture of nitrogen and hydrogen as the reactive gases. A wet cleaning process is performed on the wafer surface using a cleaning solution containing a trace amount of hydrofluoric acid.